Phosphors for field emission displays are known in the art. They are typically deposited onto a thin film of indium tin oxide (ITO) formed on a glass substrate. They are also typically covered by a film of aluminum, which is included to reflect light, dissipate electrical charge, and to provide mechanical stability to the phosphor material. This configuration suffers from the disadvantage that the phosphor extends into the strong electric field of the field emission display. Phosphor particles tend to become electrically charged, thereby increasing local electrostatic forces. These forces can cause phosphor particles to be ejected. A further disadvantage of this configuration is the loss of energy by electrons upon traversing the aluminum film. This reduces the power efficiency of the display, requiring higher anode voltages for a given brightness requirement.
Getters for field emission displays are also known in the art. Getters are used to remove contaminant gases within the field emission display, so that a suitable vacuum level is maintained therein. Prior art schemes for removing contaminant gases suffer from poor configurations with respect to the sources of the contaminant gases.
In one prior art scheme, the gettering material is disposed in a plenum region, behind the emitter plate. Access to the getter is provided by holes in the emitter plate. This prior art scheme suffers from a poor configuration of the getter with respect to the phosphor material, which is a significant source of gaseous contaminants. The contaminants must traverse the space between the anode plate and the cathode plate and thereafter travel through the holes in the cathode plate to reach the gettering material. This long path to the gettering material increases the probability that contaminants will contaminate structures, such as the emitter structures, within the display.
Accordingly, there exists a need for an improved anode structure that protects the phosphor material and improves the efficiency of the display. There further exists a need for an improved gettering configuration for a field emission display, which provides for the removal of contaminant gases proximate to the their sources.